1. Technical Field of the Invention
The present invention relates generally to a system for regulating an air/fuel ratio of an internal combustion engine. More particularly, the invention is directed to a control system for controlling an excess air ratio of an internal combustion engine using a generator-motor which is so connected to the engine as to establish the transmission of torque therebetween.
2. Background Art
Japanese Patent First Publication No. 64-66431 teaches a system which controls the operation of a generator-motor (i.e., a dynamotor) to provide an additional torque to an engine according to an opening degree of a throttle valve at an initial stage of acceleration where rising of rotation of the engine will be delayed relative to a variation in depressed position of an acceleration pedal or over the entire stage of acceleration.
The above prior art system, however, encounters a drawback in that the provision of additional torque to the engine improves an acceleration performance, but it will cause the engine speed to change rapidly, yielding a sudden variation in amount of intake air. This results in an undesirable shift in air/fuel ratio, leading to the increase in excess air ratio (i.e., a ratio of an actual amount of intake air to a theoretical amount of intake air) so that harmful exhaust gases are increased.